It would appear that the discovery of intelligent extraterrestrial life would have no effect on the "God hypothesis", not because it is a strong hypothesis but because it is a weak one - no rational means to validate or refute the hypothesis has been proposed.
It is unlikely that religion would fold because religious leaders have a talent for repositioning beliefs to the satisfaction of their sheep as can be seen from Watchtower's ability to "change feet" at the drop of a failed prophecy.
